OCB02-1012 Signalling pathways in tooth development Flashcards
What happens when oral ectoderm and odontogenic mesenchyme are cultured in isolation?
No tooth is formed
What happens when oral ectoderm and odontogenic mesenchyme are cultured together?
Oral ectoderm gives rise to the enamel and mesenchyme gives rise to dentin
What happens when oral ectoderm is combined with non-odontogenic mesenchyme?
A tooth was formed
What occurs when non-oral ectoderm tissue was combined with odontogenic mesenchyme?
No tooth was formed
What tissue initiates communication between oral ectoderm and odontogenic mesoderm?
Oral ectoderm
How does cell signalling occur?
The signalling protein binds to the torte receptor
This signal is transmitted to different proteins in the form of phosphorylation
Th signal is transmitted to the nucleus, which leads to transcription factors transcribing genes
What mesenchymal signals are present in molars?
The FGF8 is secreted by the epithelium, which diffuses into the mesenchyme
They activate the production of BARX1 and DIX2 in the molars
What mesenchymal signals are present in incisors?
BMP4 is secreted and diffuses in the mesenchyme, and induces the expression of MSX1 and ALX4
What is the purpose of SHH?
It regulates growth and determines the shape of the tooth
What dos SHH bind to? and what does this lead to?
PTCH1 receptor high leads to the activation of the GL1 transcription factor
What would occur if beads soaked in SHH were placed in toothless gaps between molars and incisors
There will be induction of another tooth germ in the gap
SHH stimulates cells to proliferate to thicken the epithelial leading to the tooth bud
How is SHH restricted to the dental epithelium?
There is complementary expression pattern between SHH and Wnt7b
Wnt7b represses the Shh expression and prevents the formation of new teeth within the dental and non-dental epithelium
What occurs when BMP ligands bind to R-I?
They recruit R-II
These receptors dimerise together and trigger BMP signalling
It induces the expression of target genes
In normal tooth development, BMP4 is secreted by epithelium and diffuses in the mesenchyme to induce the expression of MSX1
The expression of what genes induces the expression of BMP4?
Pax9 and MSX1
What occurs when MSX1 is inhibited?
BMP4 cannot e induced so the mesenchyme has no ay of signalling back to the epithelium to induce PEK
